Blind fastener

ABSTRACT

A blind fastener of two piece construction to be placed through a workpiece which is accessable only from one side which may be clamped up by conventional tooling. At installation the blind end of the core of the male core member is drawn into an annealed threaded section of the female nut member forming a bulb in the back of the work area and at the same time providing a deformed thread locking means to resist loosening under vibrations.

0 United States Patent 3,653,294

Nason [4 1 Apr. 4, 1972 54 BLIND FASTENER 3,196,918 7/1965 [72]Inventor: Edgar F. Nason, 7461 Canby Avenue, Reseda, Calif. 913353,322,449 5/1967 22 Filed: June27, 1969 3,365,998 1/1968 21 1 Appl. No.:837,220 FOREIGN PATENTS OR APPLICATIONS 928,122 5/1947 France ..85/77U.S. Cl ..85/70, 85/77, 151/31 ..F16b 13/06 Field of Search ..85/6l, 70,72, 73, 74, 77, 85/78; 151/31 References Cited UNITED STATES PATENTSPrimary Examiner-Marion Parsons, Jr. Attorney-Lyon & Lyon 57 ABSTRACT Ablind fastener of two piece construction to be placed through aworkpiece which is accessable only from one side which may be clamped upby conventional tooling. At installation the blind end of the core ofthe male core member is drawn into an annealed threaded section of thefemale nut member forming a bulb in the back of the work area and at thesame time providing a deformed thread locking means to resist looseningunder vibrations.

4 Claims, 14 Drawing Figures "PATENTEDAPR 4 I972 SHEET 2 BF 2 INVENTOR606/16 E/VASOA/ A TTGEA/EVS BLIND FASTENER OBJECTS OF THE INVENTION Theprincipal object of the present invention is to provide a two pieceblind fastener that may be clamped by normal wrenching means that isinexpensive to manufacture in that it does not require criticaltolerance.

A further object of the present invention is to provide a structurewhich is designed to give high clamp up to provide maximum integrity ofthe joint with good grip accomodation.

A still further object of the present invention is to provide a blindfastener wherein the threaded area of the sleeve and core bolt are atthe blind side of the structure so that there will be no threads in theshear area except for very short grip lengths.

A still further object of the present invention is to provide a devicein which both parts can be manufactured by conventional high speedproduction methods.

These and other objects and advantages will become apparent when thespecification is read in view of the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross sectional elevation of ablind fastener in its contracted configuration.

FIG. 2 is a cross sectional elevation of a blind fastener prior toclamping.

FIG. 3 is a partial cross sectional elevation illustrating the deformedthreads which provide the locking means.

FIG. 4 is a side elevation of the male bolt core member.

FIG. 5 is a partial cross sectional elevation of the female nut member.

FIG. 6 is a partial cross sectional elevation illustrating a countersunkhead configuration.

FIG. 7 is a cross sectional elevation of an alternate form usingunfinished threads.

FIG. 8 is a partial cross sectional elevation illustrating theunfinished threads of FIG. 7.

FIG. 9 is a cross sectional elevation of the female nut memberillustrating an alternate means for obtaining a lock between theworkpieces.

FIG. 10 is a side elevation of the locked blind fastener of FIGS. 7 and8.

FIGS. 11 and 12 are diagramatic cross sectional illustrations of thebulbing action of the blind fastener of FIG. 7.

FIG. 13 is a diagramatic cross sectional illustration of the bulbingaction of the blind fastener of FIG. 9.

FIG. 14 is a side elevation of an alternate form of a bolt of thepresent invention.

Referring now to FIGS. 1 and 2, the blind fastener consists in all ofits various modifications of an inner male core member 1 and an outerfemale nut member 2. The inner core member threadably engages the outernut member on the blind side 4 of the work area. At the other end ofinner core 1 is a holding recess 6 in the shaft and a break-off groove 8which causes all of the shaft end 10 to break ofi after wrenching hasbeen accomplished to assure a flush finish.

Referring now particularly to FIG. 2 at the blind end of the fastener acollapsing groove 12 is provided which is proximal to the blind side 4of the work piece or sheets l4 and 15 which are to be joined. Inwrenching this blind fastener the nut 16 is held and the core bolt 1 isdrawn upwardly, as the larger head end 18 is drawn into engagement withthe walls 20 of the female nut member 2. As wrenching progresses, a bulb22 is formed at the area of the collapsing groove 12 against the blindside 4 of the workpiece until the two workpieces l4 and 15 are drawntogether. As this wrenching progresses further, threads 24 in the lowerportion of the female nut are being deformed and locked against threads26 of the core member thus forming a thread lock which resists unlockingby vibration. This bulbing action may also be accomplished in smallersized blind fasteners by annealing the entire threaded section. In thisinstance, the bulb will form at the point of greatest resistance whichwould be at the blind surface 4 of the workpiece thus assuring a tightjoint of high integrity.

In all illustrations of the present invention where alloy steel boltsare used the blind end of the female nut member are annealed to allowthis bulbing action at installation.

Referring briefly now to FIGS. 9 and 10, the action of the blindfastener is the same as has just been described except that instead ofthe collapsing groove 12 of FIGS. 1 and 2 the inner surface of thefemale nut member has an undercut collapsing groove 30 above thethreaded engagement area 32. The threads cause this weakened area to bedrawn together to form bulb 34 in the blind area 4 while at the sametime deforming the unfinished threads 36 to form a thread lock.

A further variation of the present invention is illustrated by FIGS. 7,8 and 12 which employ incomplete threads 40 and 42 which start thebulbing action as these threads attempt to complete themselves. As thebulbing action continues these threads also become deformed to form athread lock.

FIG. 6 illustrates a form of the present invention employing acountersunk head or which is commonly referred to in the art as a flushrivet and FIG. 14 illustrates the employment of a tapered blind fastenerembodying the present invention.

Various changes and modifications may be made in carrying out thepresent invention without departing from the scope and spirit thereof.Insofar as these changes and modifications are within the purview of theamended claims, they are to be considered as part of the invention.

I claim:

1. A blind fastener assembly for securing a plurality of workpiecestogether comprising:

a central male core member threadably engageable by an outer female nutmember completely surrounding said central male core member;

said blind fastener having a head portion at one end of said female nutmember and a blind portion at the other end which is inserted into theworkpiece into the unaccessable blind area of said workpiece;

means on the head end of said female nut member of said blind fastenerfor holding the female nut member;

means forming a head portion on said male core member, said means beingengageable by a tool whereby said male core member can be rotatablydriven into threaded engagement with said female nut member;

means on the blind end of said male core member and said female nutmember for resisting said driving, said means being comprised of aportion of the blind end of said male core member having an externaldiameter greater than the internal diameter of said female nut member,said portion having a first plurality of threads therein and a portionof the blind end of said female nut member having a second plurality ofthreads therein, said second plurality being adaptable to beingthreadably engaged with said second plurality, whereby upon threadedengagement said first and second pluralities of threads extend from theblind end of said fastener to a point below the interface of saidworkpieces;

the combination of driving and resisting forming a bulbous member on theblind end of said fastener thereby securing said plurality ofworkpieces.

2. The combination of claim 1 including a collapsing groove in saidfemale nut member thereby decreasing resistance to 7 formation of thebulbous member at said groove.

3. A blind fastener assembly for securing a plurality of workpiecestogether comprising:

.a central male core member threadably engageable by an outer female nutmember completely surrounding said central male core member;

said blind fastener having a head portion at one end of said female nutmember and a blind portion at the other end which is inserted into theworkpiece into the unaccessable blind area of said workpiece;

means on the head end of said female nut member of said blind fastenerfor holding the female nut member;

3 4 means forming a head portion on said male core member, threadablyengaged with said first plurality whereby upon said means beingengageable by a tool whereby said male threaded engagement said firstand second pluralities of core member can be rotatably driven intothreaded enunfinished threads extend from the blind end of said gagementwith said female nut member; fastener to a point below the interface ofsaid workpiece; means on the blind end of aid male ore b r d id 5 thecombination of driving and resisting forming a bulbous female nut memberfor resisting said driving, said means member on the blind end of saidfastener thereby securcomprising a portion of the blind end of said malecore inssaid plurality ofworkpieces- 4. The combination of claim 3including a collapsing groove in said female nut member therebydecreasing resistance to formation of the bulbous member at said groove.

member having a first plurality of unfinished threads therein and aportion of the blind end of said female nut member having a secondplurality of unfinished threads flierein, said second plurality beingadaptable to being

1. A blind fastener assembly for securing a plurality of workpiecestogether comprising: a central male core member threadably engageable byan outer female nut member completely surrounding said central male coremember; said blind fastener having a head portion at one end of saidfemale nut member and a blind portion at the other end which is insertedinto the workpiece into the unaccessable blind area of said workpiece;means on the head end of said female nut member of said blind fastenerfor holding the female nut member; means forming a head portion on saidmale core member, said means being engageable by a tool whereby saidmale core member can be rotatably driven into threaded engagement withsaid female nut member; means on the blind end of said male core memberand said female nut member for resisting said driving, said means beingcomprised of a portion of the blind end of said male core member havingan external diameter greater than the internal diameter of said femalenut member, said portion having a first plurality of threads therein anda portion of the blind end of said female nut member having a secondplurality of threads therein, said second plurality being adaptable tobeing threadably engaged with said second plurality, whereby uponthreaded engagement said first and second pluralities of threads extendfrom the blind end of said fastener to a point below the interface Ofsaid workpieces; the combination of driving and resisting forming abulbous member on the blind end of said fastener thereby securing saidplurality of workpieces.
 2. The combination of claim 1 including acollapsing groove in said female nut member thereby decreasingresistance to formation of the bulbous member at said groove.
 3. A blindfastener assembly for securing a plurality of workpieces togethercomprising: a central male core member threadably engageable by an outerfemale nut member completely surrounding said central male core member;said blind fastener having a head portion at one end of said female nutmember and a blind portion at the other end which is inserted into theworkpiece into the unaccessable blind area of said workpiece; means onthe head end of said female nut member of said blind fastener forholding the female nut member; means forming a head portion on said malecore member, said means being engageable by a tool whereby said malecore member can be rotatably driven into threaded engagement with saidfemale nut member; means on the blind end of said male core member andsaid female nut member for resisting said driving, said means comprisinga portion of the blind end of said male core member having a firstplurality of unfinished threads therein and a portion of the blind endof said female nut member having a second plurality of unfinishedthreads therein, said second plurality being adaptable to beingthreadably engaged with said first plurality whereby upon threadedengagement said first and second pluralities of unfinished threadsextend from the blind end of said fastener to a point below theinterface of said workpiece; the combination of driving and resistingforming a bulbous member on the blind end of said fastener therebysecuring said plurality of workpieces.
 4. The combination of claim 3including a collapsing groove in said female nut member therebydecreasing resistance to formation of the bulbous member at said groove.